In practice, road pavers are used to install new road surfaces by means of a paving screed installed on them. The paving material to be used comes from a material hopper of the road paver that is disposed at the front of the road paver when seen in the installation direction. Through a material conveyor, the paving material is transported out of the material hopper rearwards to the paving screed, spread out by said paving screed by means of a spreading auger and finally installed to form a new road surface under the paving screed by means of heated densification aggregates.
To enable the installation of an even road surface on a ground, on which the road paver is moved, the paving screed is fastened on the chassis of the road paver by means of screed arms with an adjustable height. Leveling of the paving screed can be controlled by a control unit of the road paver. In this process, leveling of the paving screed depends on the surface texture of the ground and/or on the target thickness of the road surface to be installed.
It is known that, for leveling a paving screed of a road paver, an elongated, rigid measurement bar is attached laterally on the road paver that positions a plurality of sensors on one hand above the ground, on which the road paver moves, as well as above the newly installed road surface layer behind the paving screed. It is problematic for known measurement bar supports that they are heavy, that their assembly is time-consuming and that in particular the installation on the road paver requires a high degree of skill and several people.
For example, the DE 602 26 237 T2 shows a measurement bar device with bars disposed on top of one another that can be extended telescopically along the road paver to position sensors for a height measurement above the ground next to the sides of the road paver. The respective telescopic bar segments can be fastened at a desired point by means of fixtures provided on it. In addition, the respective height positions of the sensors can be adjusted. This comes with the disadvantages of the telescopic measurement bars having a heavy weight so that they can only be used on special road paver types. In addition, several people are required for installation and/or deinstallation of the measurement bar device on and/or from the road paver. Besides, the possibilities with regard to installing the sensors at a certain height are limited. Finally, the sensors are held on the measurement bar by different clamping forces, which depends on the force of the adjuster, so that a new adjustment of the measurement bar device could lead to difficulties.
U.S. Pat. No. 5,975,473 A discloses a measurement bar device that is attached on the sides of a road paver. The measurement bar device is fastened on a screed arm of the road paver by means of flexible swivel arms. Furthermore, the measurement bar device comprises a measurement bar, which is supported laterally along the road paver, with a central bar as well as with extending bars fastened on the ends of said central bar. Height measurement sensors are disposed respectively on the central bar as well as on the extending bars. The respective extending bars can be swiveled inwards in relation to the central bar in a horizontal direction so that the sensor fastened on the rear extending bar at the back of the road paver can be positioned above the newly installed road surface layer behind the paving screed. In this measurement bar device, the respective segments, which are connected flexibly to one another, are coupled by means of threaded screw joints. Assembly is therefore very work-intensive and time-consuming. In addition, different clamping forces act on the respective threaded screw joints, which ultimately depends on the strength of the operator who adjusts the holding device. This complicates installation and adjustment of the holding device and keeps the device from being equally easy to install for everyone. Moreover, it is not rare for such a complex measurement bar device that individual components, in particular loose screw levers, screws and brackets, get lost at the construction site. Eventually, the possibilities to set appropriate height positions for the sensors are limited for this measurement bar device.
DE 691 26 017 T2 discloses a road paver with a measurement bar fastened on it, which is formed rigidly and positioned laterally of a screed arm of the road paver above the ground. This comes with the disadvantage of the measurement bar being in particular only usable in a limited number of road paver types due to the rigid design of said measurement bar.